Method for manufacturing display and display

ABSTRACT

A display with: a plurality of lower electrodes formed over a substrate; an auxiliary electrode formed between the lower electrodes and having a film thickness which is less than a film thickness of the plurality of lower electrodes; an insulating film formed over the substrate and including openings that expose the lower electrodes and a connection hole that reaches the auxiliary electrode; a light-emitting functional layer formed on the lower electrodes exposed via the openings, the insulating film having a flat surface; and an upper electrode formed over the lower electrodes and connected to the auxiliary electrode via the connection hole.

RELATED APPLICATION DATA

This application is a division of U.S. patent application Ser. No.11/842,511, filed Aug. 21, 2007, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims priority to Japanese Patent Application No.2006-226003 filed in the Japan Patent Office on Aug. 23, 2006, theentirety of which also is incorporated by reference herein to the extentpermitted by law.

BACKGROUND OF THE INVENTION

The present invention relates to a method for manufacturing a displaythat has organic electro-luminescence elements each including an organiclight-emitting layer, and a display.

An organic electro-luminescence element, which employselectro-luminescence (hereinafter, represented as EL) of an organicmaterial, is a light-emitting element that includes a light-emittinglayer composed of an organic material and so on between a lowerelectrode and an upper electrode and can emit light with high luminancethrough low-voltage DC driving.

In recent years, attention is being paid on a transfer method as atechnique for forming organic layer patterns in manufacturing of afull-color display employing the organic EL elements. In particular, acontact transfer method allows an organic layer to be transferred to atransfer-destination substrate in the state in which the multilayerstructure of the organic layer formed over a donor film as the transferorigin is kept as it is. Therefore, this method permits simplificationof steps for manufacturing a display.

In the contact transfer method, initially a donor film over which anorganic layer is deposited in advance is brought into close contact witha substrate over which a lower electrode is patterned in advance.Subsequently, only the area corresponding to the part over which theorganic layer should be formed is irradiated with laser light. Thiscauses only the organic layer part irradiated with the laser light to beselectively transferred from the donor film onto the lower electrodeover the substrate.

A structure for the contact transfer method has been proposed to preventtroubles of the transfer due to insufficiency of the close contactbetween a donor film and a substrate even when recesses and projectionsexist on the surface of the substrate over which an organic layer is tobe transferred. Specifically, in this structure, the taper angles of therecesses and projections are set to 40° or smaller, and the heights ofthe steps of the recesses and projections are set to 3000 Å or smallerto prevent the troubles (refer to Japanese Patent Laid-Open No.2005-165324 (Paragraphs 0013 and 0016, in particular)).

SUMMARY OF THE INVENTION

As the system for driving a display employing organic EL elements, asimple-matrix system and an active-matrix system are available. When thenumber of pixels is large, the active-matrix system is more suitable.

It is preferable that an active-matrix display have a so-called top-facelight extraction structure (hereinafter, referred to as a top-emissionstructure) for extracting light from the opposite side of a substrate inorder to assure a high aperture ratio of organic EL elements. In atop-emission display, the upper electrode is formed of a transparent orsemi-transparent material. However, the upper electrode composed of atransparent or semi-transparent material has high resistance. Therefore,a voltage gradient is generated in the upper electrode and thus avoltage drop arises therein, which significantly deteriorates thedisplaying performance. To address this, a structure has been proposedin which an auxiliary electrode for the upper electrode is providedamong the respective pixels to prevent the voltage drop.

However, when the above-described contact transfer method is applied tomanufacturing of a display in which an auxiliary electrode is provided,if an error of the laser light irradiation position occurs, an organiclayer will be transferred also onto the auxiliary electrode, which willcause contact failure between the upper electrode and the auxiliaryelectrode. This precludes the effective prevention of the voltage drop,and thus makes it difficult to enhance the displaying performance.

As a countermeasure to prevent this problem, a method would be availablein which the lower electrode and the auxiliary electrode are disposed atpositions that are sufficiently far away from each other so that thelaser light irradiation area will not overlap with the auxiliaryelectrode. However, this method imposes severe limitations on the pixellayout, and leads to a low aperture ratio.

There is a need for the present invention to provide a method in whichin formation of an organic layer on a lower electrode by a contacttransfer method, formation of the organic layer on an auxiliaryelectrode can be prevented without the lowering of the pixel apertureratio.

In a method for manufacturing a display according to an embodiment ofthe present invention, the following steps are sequentially carried out.Initially, a substrate over which a plurality of lower electrodes and aplurality of auxiliary electrodes are formed and a donor film over whicha light-emitting functional layer is formed are prepared. Subsequently,the substrate and the donor film are disposed so that the light-emittingfunctional layer contacts with the lower electrodes and does not contactwith the auxiliary electrodes. In this state, the donor film isirradiated with an energy beam, and thereby the light-emittingfunctional layer is selectively transferred onto the lower electrodes.Thereafter, an upper electrode is formed to form light-emittingelements. The light-emitting functional layer is interposed between theupper and lower electrodes, and the upper electrode is connected to theauxiliary electrodes.

In such a manufacturing method, even when a positional error of the areairradiated with the energy beam occurs, the light-emitting functionallayer is not transferred on the auxiliary electrode because a gap isprovide between the auxiliary electrode at the bottom of the connectionhole and the donor film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing major part of one configurationexample of a donor film used in a manufacturing method according to anembodiment of the present invention;

FIGS. 2A to 2F are sectional views showing steps of a manufacturingmethod according to a first embodiment of the present invention;

FIG. 3 is a plan view showing one example of the layout of lowerelectrodes and an auxiliary electrode in an embodiment of the presentinvention;

FIGS. 4A to 4F are sectional views showing steps of a manufacturingmethod according to a second embodiment of the present invention;

FIGS. 5A to 5F are sectional views showing steps of a manufacturingmethod according to a third embodiment of the present invention;

FIGS. 6A to 6F are sectional views showing steps of a manufacturingmethod according to a fourth embodiment of the present invention;

FIGS. 7A to 7F are sectional views showing steps of a manufacturingmethod according to a fifth embodiment of the present invention;

FIGS. 8A to 8C are sectional views showing steps of a modificationexample of an embodiment of the present invention; and

FIG. 9 is a plan view showing one example of the layout of lowerelectrodes, an auxiliary electrode, and an upper electrode in apassive-matrix display.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in detail belowbased on the drawings.

<Donor Film>

A donor film 1 shown in FIG. 1 is used for formation of an organic layerof organic EL elements in manufacturing of a display that employs theorganic EL elements as its light-emitting elements. In this donor film1, an organic layer (i.e., light-emitting functional layer) 5 as atransfer target is provided over a base film 2 with a photothermalconversion layer 3 and a protective layer 4.

1) Base Film 2

As the base film 2, a transparent polymer film can be used. Examples ofthe transparent polymer include, but not limited to, polycarbonate,polyethylene terephthalate, polyester, polyacryl, polyepoxy,polyethylene, polystyrene, and polyethersulfone. It is preferable thatthe film thickness of the base film 2 is about 10 to 600 μm, and athickness of about 50 to 200 μm is more preferable.

2) Photothermal Conversion Layer 3

The photothermal conversion layer 3 is a film that has a function toabsorb light and generate heat efficiently. Examples of such a filminclude, but not limited to, an aluminum film, metal film composed of anoxide/nitride of aluminum, and film obtained by dispersing carbon black,graphite, infrared dye, or the like in a polymer material.

3) Protective Layer 4

The protective layer 4 is disposed between the photothermal conversionlayer 3 and the organic layer 5, which is a transfer layer, and preventscontamination from the photothermal conversion layer 3 to the organiclayer 5. Examples of the material of the protective layer 4 include, butnot limited to, poly-α-methylstyrene. It is also possible for theprotective layer 4 to have also a function to assist separation of theorganic layer 5 and a function to control the heat generated by thephotothermal conversion layer 3.

The provision of the protective layer 4 depends on need.

Although not shown in the drawing, a gas generation layer may beprovided on the protective layer 4 according to need. The gas generationlayer is to absorb light or heat to generate and discharge a gas (e.g.,nitrogen gas) through decomposition reaction for efficient transfer.Examples of the material thereof include pentaerythritol tetranitrateand trinitrotoluene. However, the present invention is not particularlylimited thereto.

4) Organic Layer 5

The organic layer 5 may have a single-layer structure or alternativelymay have a multi-layer structure. It is important for the organic layer5 to have a layer structure designed depending on the characteristicsnecessary for organic EL elements to be manufactured by using the donorfilm. Examples of the structure of the organic layer 5 include thefollowing single-layer structures and multi-layer structures.

(1) organic light-emitting layer(2) electron transport layer(3) hole transport layer/organic light-emitting layer(4) organic light-emitting layer/electron transport layer(5) hole transport layer/organic light-emitting layer/electron transportlayer(6) hole injection layer/hole transport layer/organic light-emittinglayer/electron transport layer(7) hole injection layer/hole transport layer/organic light-emittinglayer/blocking layer/electron transport layer

Each of the layers in these structures (1) to (7) may be a single layeror alternatively may have a multi-layer structure. In some cases, themulti-layer structures (3) to (7) possibly have the reverselayer-stacking order depending on the configuration of organic ELelements. Each layer in the structures (1) to (7) can be deposited by anexisting method. For example, an organic light-emitting layer can beformed through direct deposition of an organic light-emitting materialby a dry process such as vacuum evaporation, EB, MBE, or sputtering.However, the present invention is not particularly limited thereto.

FIG. 1 shows, as one example, the organic layer 5 that has the structureobtained by reversing the structure (6). Specifically, the organic layer5 has a structure in which an electron transport layer 5 a, an organiclight-emitting layer 5 b, a hole transport layer 5 c, and a holeinjection layer 5 d are deposited in that order from the base film side.

In the case of manufacturing of a full-color display, in order to formorganic EL elements of light-emission colors of red, green and blue overa substrate, three kinds of donor films 1 corresponding to theselight-emission colors are prepared. In these donor films 1, at least theorganic light-emitting layers 5 b have different configurations eachformed by using a light-emitting material specific to a respective oneof the light-emission colors.

As one specific example, in the donor film 1 used for formation of blueorganic EL elements, Alq3 [tris(8-quinolinolato)aluminum(III)] isevaporated to a film thickness of 20 nm as the electron transport layer5 a that serves also as a light-emitting layer. On the electrontransport layer 5 a, a material layer is deposited by evaporation as theorganic light-emitting layer 5 b. For example, this material layer has afilm thickness of about 25 nm and arises from doping of ADN (anthracenedinaphtyl), which is an electron transport host material, with 2.5-wt. %4,4′-bis[2-{4-(N,N-diphenylamino)phenyl}vinyl]biphenyl (DPAVBi), whichis a blue-light-emitting guest material. Subsequently, as the holetransport layer 5 c, α-NPD [4,4-bis(N-1-naphthyl-N-phenylamino)biphenyl]is evaporated to a film thickness of 30 nm. At last, as the holeinjection layer 5 d, m-MTDATA[4,4,4-tris(3-methylphenylphenylamino)triphenylamine] is evaporated to afilm thickness of 10 nm.

First Embodiment

FIGS. 2A to 2F are sectional views for explaining steps of amanufacturing method that employs a donor film having theabove-described one configuration example according to a firstembodiment of the present invention. These sectional views of stepscorrespond to a section of one pixel in the display area.

Referring initially to FIG. 2A, a thin film transistor Tr, capacitiveelement, and resistive element (not shown) included in a pixel circuitare formed on a substrate 10 composed of e.g. an optically transparentmaterial. Subsequently, a first insulating film 12 that covers theseelements (thin film transistor Tr, in the drawing) is deposited.Furthermore, on the first insulating film 12, a source electrodeinterconnect 14 s and a drain electrode interconnect 14 d that areconnected to the transistor Tr, and a signal line, power supply line,and so on that are connected to these interconnects 14 s and 14 d areadequately formed.

Thereafter, a second insulating film 16 is formed on the firstinsulating film 12 in such a manner as to cover these interconnects. Inthe present example, this second insulating film 16 is formed as aplanarization insulating film composed of e.g. an organic insulatingmaterial such as polyimide or photoresist or an inorganic insulatingmaterial such as SOG. In this second insulating film 16, a connectionhole 16 a reaching the drain electrode interconnect 14 d is formed.

Subsequently, a lower electrode 18 of an organic EL element is formed onthe planarization surface of the second insulating film 16 formed as aplanarization insulating film. As shown in the layout diagram of FIG. 3for example, the lower electrodes 18 are formed into a matrix in thedisplay area as pixel electrodes each used for a respective one ofpixels, and each of the lower electrodes 18 is connected through theconnection hole 16 a to the drain electrode interconnect 14 d.

The lower electrode 18 is used as an anode electrode in the presentexample. If the display to be manufacturing in the present example is atop-emission display, the lower electrode 18 is formed by using amaterial that is highly reflective for visible light. In contrast, ifthe display is a transmissive one, the lower electrode 18 is formed byusing a material that is transparent to visible light.

When the display is a top-emission one, the lower electrode 18 servingas an anode electrode is formed by using any of the following conductivematerials having high reflectivity for visible light or an alloy of anyof the materials: silver (Ag), aluminum (Al), chromium (Cr), iron (Fe),cobalt (Co), nickel (Ni), copper (Cu), tantalum (Ta), tungsten (W),platinum (Pt), and gold (Au).

When the display is a transmissive one and the lower electrode 18 isused as an anode electrode, the lower electrode 18 is formed by using aconductive material offering high transmittance for visible light, suchas indium tin oxide (ITO) or indium zinc oxide (IZO).

When an organic EL element is a top-emission element and the lowerelectrode 18 is used as a cathode electrode, the lower electrode 18 isformed by using a material having high reflectivity for visible light,of conductive materials having a small work function, such as aluminum(Al), indium (In), and magnesium (Mg)-silver (Ag) alloy. When an organicEL element is a transmissive one and the lower electrode 18 is used as acathode electrode, the lower electrode 18 is formed by using aconductive material that has a small work function and offers hightransmittance for visible light.

On the second insulating film (planarization insulating film) 16, anauxiliary electrode 20 is formed in such a manner as to be kept isolatedfrom the lower electrode 18. This auxiliary electrode 20 may be suppliedwith a common potential in the display area. As shown in the layoutdiagram of FIG. 3 for example, the auxiliary electrode 20 is provided onrows and columns among the lower electrodes 18 arranged in a matrix.

In the first embodiment in particular, it is important that the filmthickness of the auxiliary electrode 20 be set smaller than that of thelower electrode 18. It is preferable that the relationship t2≧t1+about500 nm be satisfied when t1 and t2 denote the film thicknesses of theauxiliary electrode 20 and the lower electrode 18, respectively. Thisrelationship allows the surface of the lower electrode 18 to bepositioned higher than that of the auxiliary electrode 20.

The auxiliary electrode 20 may be formed in a step different from thestep for forming the lower electrode 18 separately. Alternatively, itmay be formed in the same step, and then the film thickness thereof maybe adjusted through etching for decreasing only the thickness of theauxiliary electrode 20.

Referring next to FIG. 2B, a third insulating film 22 is formed in sucha manner as to cover the lower electrode 18 and the auxiliary electrode20. The third insulating film 22 is formed as a planarization insulatingfilm composed of e.g. an organic insulating material such as polyimideor photoresist or an inorganic insulating material such as SOG. Thus,the thickness of the third insulating film 22 on the auxiliary electrode20 is larger than that on the lower electrode 18.

Subsequently, in the third insulating film 22, a opening 22 a thatwidely exposes the center part of the lower electrode 18 with theperipheral edge thereof covered, and a connection hole 22 b reaching theauxiliary electrode 20 are formed. Thus, the depth of the connectionhole 22 b on the auxiliary electrode 20 is larger than that of theopening 22 a on the lower electrode 18. In this aperture formation step,it is preferable to carry out etching of which condition is so set thatthe taper angle of the sidewall of the opening 22 a will be set to 30°or smaller.

Referring next to FIG. 2C, a donor film 1 is disposed on one surfaceside of the substrate 10 on which the lower electrode 18 is formed.Specifically, the organic layer side of the donor film 1 with theconfiguration described with FIG. 1 is brought into close contact withthe lower electrode side of the substrate 10. At this time, a gap d isprovided between the organic layer 5 and the auxiliary electrode 20exposed at the bottom of the connection hole 22 b, which is deeper thanthe opening 22 a. On the other hand, the organic layer 5 is brought intoclose contact with the lower electrode 18 exposed at the bottom of theopening 22 a, which is shallower than the connection hole 22 b.

In this state, from the donor film side, the part corresponding to thelower electrodes 18 of selected pixels is irradiated with an energy beamsuch as laser light h. For example, in the state in which the donor film1 for red organic EL elements is brought into close contact with thesubstrate 10, only the area corresponding to the lower electrodes 18formed in red pixels is selectively irradiated with the laser light h.Thereby, the organic layer 5 over the donor film 1 is selectivelytransferred onto the lower electrodes 18.

Used as the laser light h is light having a wavelength that permits thematerial of the photothermal conversion layer (see FIG. 1) of the donorfilm 1 to efficiently absorb the light. For example, when thephotothermal conversion layer is formed of a polymer layer containingcarbon black, e.g. a semiconductor CW laser source is used to emitinfrared laser light having a wavelength of 800 nm, so that thephotothermal conversion layer (see FIG. 1) of the donor film 1 is causedto absorb the laser light h and heat generated therein is used totransfer the organic layer 5 deposited over the donor film 1 onto thesubstrate 10.

In the contact transfer, it is important that the area to be irradiatedwith the laser light h is so designed that the laser light h will beemitted to a sufficient area corresponding to the whole of the lowerelectrode 18 exposed via the opening 22 a and thereby the exposed faceof the lower electrode 18 in a selected pixel will be completely coveredby the organic layer 5. Therefore, when a laser emission apparatusincludes an accurate alignment mechanism, the laser light h having aproperly adjusted spot diameter is emitted along alignment marks (e.g.,lower electrodes 18) over the substrate 10.

Furthermore, it is also possible to use a mask having aperturescorresponding to the part to be irradiated with the laser light h. Inthis case, the mask (not shown) is disposed over the donor film 1, andthe laser light h having a spot diameter larger than the diameter of theaperture is emitted. This allows the laser light h to be accuratelyemitted onto the requisite area via the mask apertures.

In the case of using a mask, a wide area (e.g., the entire face) may becollectively irradiated with laser light. This permits an intended placeto be irradiated with the laser light h in a short time.

Referring next to FIG. 2D, the donor film 1 is separated from thesubstrate 10. On the lower electrodes 18 of the red pixels, the organiclayer 5 is formed.

Thereafter, by using the donor film 1 for green organic EL elements, thesteps of FIGS. 2C and 2D are carried out to selectively form the organiclayer 5 for green light emission on the lower electrodes 18 formed ingreen pixels. In addition, by using the donor film 1 for blue organic ELelements, the steps of FIGS. 2C and 2D are carried out to selectivelyform the organic layer 5 for blue light emission on the lower electrodes18 formed in blue pixels.

Subsequently, as shown in FIG. 2E, an upper electrode 30 common to therespective pixels is formed on the whole of the display area over thesubstrate 10. The upper electrode 30 is connected to the auxiliaryelectrode 20. The upper electrode 30 is isolated from the lowerelectrode 18 by the organic layer 5 and the third insulating film 22.

In the present example, the upper electrode 30 is formed as a cathodeelectrode because the lower electrode 18 is formed as an anodeelectrode. When the display to be manufactured is a top-emission one,the upper electrode 30 is formed by using a material that is transparentor semi-transparent to visible light. When the display is a transmissiveone, the upper electrode 30 is formed by using a material having highreflectivity for visible light.

When the display is a top-emission one, it is preferable that the upperelectrode 30 serving as a cathode electrode be formed of a materialhaving a small work function so that electrons can be efficientlyinjected into the organic layer 5. Furthermore, to promote the electroninjection, the upper electrode 30 may have a multi-layer structureincluding an inorganic thin film such as a LiF film. In the presentexample, a metal thin film that offers high transmittance, preferablytransmittance of 30% or higher, is used as the upper electrode 30. Forexample, an Mg—Ag alloy film is formed by co-sputtering to a filmthickness of 14 nm.

When the display is a transmissive one, the upper electrode 30 to serveas a cathode electrode is formed by using a conductive material that hasa small work function and high reflectivity for visible light.

The formation of the upper electrode 30 is carried out by using adeposition method in which the energy of deposition particles is so lowthat no influence is given to the underlying layers, such as evaporationor chemical vapor deposition (CVD). Furthermore, it is preferable thatthe formation of the upper electrode 30 be carried out in the sameapparatus as that for the formation of the organic layer 5 successivelyto the formation of the organic layer 5 without exposure of the organiclayer 5 to the atmosphere, to prevent the deterioration of the organiclayer 5 due to water in the atmosphere.

Through the above-described steps, the organic electro-luminescenceelements EL in which the organic layer 5 is interposed between the lowerelectrode 18 and the upper electrode 30 are formed over the substrate10, corresponding to the respective openings 22 a. For the organicelectro-luminescence elements EL, the upper electrode 30 is connected tothe auxiliary electrode 20, which prevents a voltage drop.

Referring next to FIG. 2F, an insulating or conductive protective film32 is provided on the upper electrode 30. Used for the provision of theprotective film 32 is a deposition method in which the energy ofdeposition particles is so low that no influence is given to theunderlying layers, such as evaporation or chemical vapor deposition(CVD). Furthermore, the formation of the protective film 32 is carriedout in the same apparatus as that for the formation of the upperelectrode 30 successively without exposure of the upper electrode 30 tothe atmosphere. This prevents the deterioration of the organic layer 5due to water and oxygen in the atmosphere.

The protective film 32 is formed to a sufficiently large film thicknessby using a material with low water permeability and low water absorptionin order to prevent water from reaching the organic layer 5. Moreover,when the display is a top-emission one, this protective film 32 isformed by using a material that allows the passage of light generated bythe organic layer 5.

In the present example, the protective film 32 is formed by using aninsulating material. For such a protective film 32, an inorganicamorphous insulating material such as amorphous silicon (α-Si),amorphous silicon carbide (α-SiC), amorphous silicon nitride(α-Si1-xNx), or amorphous carbon (α-C) can be preferably used. Such aninorganic amorphous insulating material includes no grain and thus haslow water permeability.

For example, in the case of forming the protective film 32 composed ofan amorphous silicon nitride, it is formed by CVD to a film thickness of2 to 3 μm. In this film deposition, it is desirable that the depositiontemperature be set to a room temperature in order to prevent luminancelowering due to the deterioration of the organic layer 5 and thedeposition condition be so set that the film stress can be minimized inorder to prevent separation of the protective film 32.

In the case of forming the protective film 32 by using a conductivematerial, a transparent conductive material such as ITO or IZO is used.

After the formation of the protective film 32, a counter substrate 36 isfixed over the protective film 32 with a UV-curable resin 34 accordingto need, so that a display 38 is completed.

Second Embodiment

FIGS. 4A to 4F are sectional views for explaining steps of amanufacturing method that employs a donor film having theabove-described one configuration example according to a secondembodiment of the present invention. These sectional views of stepscorrespond to a section of one pixel in the display area. The samecomponents in the second embodiment as those in the first embodiment aregiven the same numerals, and a redundant description thereof is omitted.

Referring initially to FIG. 4A, elements such as a thin film transistorTr included in a pixel circuit are formed on a substrate 10, and theseelements are covered by a first insulating film 12. On the firstinsulating film 12, a source electrode interconnect 14 s and a drainelectrode interconnect 14 d that are connected to the thin filmtransistor Tr, and a signal line, power supply line, and so on that areconnected to these interconnects 14 s and 14 d are adequately formed.

Subsequently, a second insulating film 16 is formed on the firstinsulating film 12 in such a manner as to cover these interconnects. Itis preferable that this second insulating film 16 be formed as aplanarization insulating film. In this second insulating film 16, aconnection hole 16 a reaching the drain electrode interconnect 14 d isformed.

Subsequently, a lower electrode 18 of an organic EL element and anauxiliary electrode 40 are formed on the planarization surface of thesecond insulating film 16 formed as a planarization insulating film. Asshown in the layout diagram of FIG. 3, the lower electrodes 18 areformed into a matrix in the display area as pixel electrodes each usedfor a respective one of pixels, and each of the lower electrodes 18 isconnected via the connection hole 16 a to the drain electrodeinterconnect 14 d. The auxiliary electrode 40 may be supplied with acommon potential in the display area, and is provided on rows andcolumns among the lower electrodes 18 arranged in a matrix. The lowerelectrode 18 and the auxiliary electrode 40 may be formed in the samestep.

Referring next to FIG. 4B, a third insulating film 22 is formed in sucha manner as to cover the lower electrode 18 and the auxiliary electrode40. The third insulating film 22 is formed as a planarization insulatingfilm composed of e.g. an organic insulating material such as polyimideor photoresist or an inorganic insulating material such as SOG.

Subsequently, in the third insulating film 22, a opening 22 a thatexposes the lower electrode 18, and a connection hole 22 b reaching theauxiliary electrode 40 are formed. A feature of the second embodiment isthat the size of the opening 22 a is so increased that the sidewall ofthe lower electrode 18 is also exposed to reduce the ratio of theaperture size of the connection hole 22 b to that of the opening 22 a.

After the above-described steps, the steps shown in FIGS. 4C to 4F arecarried out similarly to the first embodiment.

Referring initially to FIG. 4C, a donor film 1 is disposed on onesurface side of the substrate 10 on which the lower electrode 18 isformed. Specifically, the organic layer side of the donor film 1 withthe configuration described with FIG. 1 is brought into close contactwith the lower electrode side of the substrate 10. At this time, theorganic layer 5 is brought into close contact with the lower electrode18 exposed at the bottom of the opening 22 a having the increased size.On the other hand, a gap d is provided between the organic layer 5 andthe auxiliary electrode 40 exposed at the bottom of the connection hole22 b, of which aperture size ratio is sufficiently decreased withrespect to the increased size of the opening 22 a.

In this state, from the donor film side, the part corresponding to thelower electrodes 18 of selected pixels is irradiated with an energy beamsuch as laser light h. Thereby, the organic layer 5 over the donor film1 is selectively transferred onto the lower electrodes 18.

Referring next to FIG. 4D, the donor film 1 is separated from thesubstrate 10.

Thereafter, through repetition of the steps of FIGS. 4C to 4D, theorganic layer 5 for each of the remaining colors is selectively formedon the lower electrodes 18 formed in pixels of a respective one of thecolors.

Subsequently, as shown in FIG. 4E, an upper electrode 30 common to therespective pixels is formed on the whole of the display area over thesubstrate 10. The upper electrode 30 is connected to the auxiliaryelectrode 40.

Thereafter, as shown in FIG. 4F, an insulating or conductive protectivefilm 32 is provided on the upper electrode 30. Furthermore, a countersubstrate 36 is fixed over the protective film 32 with a UV-curableresin 34 according to need, so that a display 38 a is completed.

Third Embodiment

FIGS. 5A to 5F are sectional views for explaining steps of amanufacturing method that employs a donor film having theabove-described one configuration example according to a thirdembodiment of the present invention. These sectional views of stepscorrespond to a section of one pixel in the display area. The samecomponents in the third embodiment as those in the second embodiment aregiven the same numerals, and a redundant description thereof is omitted.

Referring initially to FIG. 5A, elements such as a thin film transistorTr included in a pixel circuit are formed on a substrate 10, and theseelements are covered by a first insulating film 12. On the firstinsulating film 12, a source electrode interconnect 14 s and a drainelectrode interconnect 14 d that are connected to the thin filmtransistor Tr, and a signal line, power supply line, and so on that areconnected to these interconnects 14 s and 14 d are adequately formed.

Subsequently, similarly to the second embodiment, a second insulatingfilm 16 is formed on the first insulating film 12 and a connection hole16 a reaching the drain electrode interconnect 14 d is provided,followed by formation of a lower electrode 18 of an organic EL elementand an auxiliary electrode 40 on the planarization surface of the secondinsulating film 16.

Referring next to FIG. 5B, a third insulating film 22 is formed in sucha manner as to cover the lower electrode 18 and the auxiliary electrode40. The third insulating film 22 is formed as a planarization insulatingfilm composed of e.g. an organic insulating material such as polyimideor photoresist or an inorganic insulating material such as SOG.

Subsequently, in the third insulating film 22, a opening 22 a thatwidely exposes the center part of the lower electrode 18 with theperipheral edge thereof covered, and a connection hole 22 b reaching theauxiliary electrode 40 are formed. A feature of the third embodiment isthat the opening 22 a and the connection hole 22 b are formed in orderthat the taper angle θ1 of the sidewall of the opening 22 a (it ispreferable that the taper angle θ1 be equal to or smaller than 30°) issmaller than the taper angle θ2 of the sidewall of the connection hole22 b.

The formation of such opening 22 a and connection hole 22 b is carriedout through e.g. two times of etching with use of resist patterns.Specifically, on the third insulating film 22, a first resist patternhaving an aperture corresponding to the opening 22 a with the taperangle θ1 is formed. Subsequently, from above the first resist pattern,etching is performed for the third insulating film 22 and the firstresist pattern, so that the opening 22 a having the taper angle θ1 isformed in the third insulating film 22. Similarly, by etching with useof a second resist pattern, the connection hole 22 b having the taperangle θ2 is formed in the third insulating film 22.

The taper angles of apertures provided in the first and second resistpatterns can be adjusted based on the exposure amount and so on at thetime of the resist formation.

After the above-described steps, the steps shown in FIGS. 5C to 5F arecarried out similarly to the first embodiment.

Referring initially to FIG. 5C, a donor film 1 is disposed on onesurface side of the substrate 10 on which the lower electrode 18 isformed. Specifically, the organic layer side of the donor film 1 withthe configuration described with FIG. 1 is brought into close contactwith the lower electrode side of the substrate 10. At this time, a gap dis provided between the organic layer 5 and the auxiliary electrode 40exposed at the bottom of the connection hole 22 b, of which sidewalltaper angle θ2 is larger than the sidewall taper angle θ1 of the opening22 a. On the other hand, the organic layer 5 is brought into closecontact with the lower electrode 18 exposed at the bottom of the opening22 a, of which sidewall taper angle θ1 is smaller than the sidewalltaper angle θ2 of the connection hole 22 b.

In this state, from the donor film side, the part corresponding to thelower electrodes 18 of selected pixels is irradiated with an energy beamsuch as laser light h. Thereby, the organic layer 5 over the donor film1 is selectively transferred onto the lower electrodes 18.

Subsequently, as shown in FIG. 5D, the donor film 1 is separated fromthe substrate 10.

Thereafter, through repetition of the steps of FIGS. 5C and 5D, theorganic layer 5 for each of the remaining colors is selectively formedon the lower electrodes 18 formed in pixels of a respective one of thecolors.

Subsequently, as shown in FIG. 5E, an upper electrode 30 common to therespective pixels is formed on the whole of the display area over thesubstrate 10. The upper electrode 30 is connected to the auxiliaryelectrode 40, which is exposed also after the transfer of the organiclayer 5.

Through this formation of the upper electrode 30, the organicelectro-luminescence elements EL in which the organic layer 5 isinterposed between the lower electrode 18 and the upper electrode 30 areformed over the substrate 10, corresponding to the respective openings22 a. For the organic electro-luminescence elements EL, the upperelectrode 30 is connected to the auxiliary electrode 40, which preventsa voltage drop.

After the formation of the upper electrode 30, as shown in FIG. 5F, aninsulating or conductive protective film 32 is provided on the upperelectrode 30. Furthermore, a counter substrate 36 is fixed over theprotective film 32 with a UV-curable resin 34 according to need, so thata display 38 b is completed.

The above-described first, second and third embodiments can beadequately combined with each other, and the combining can enhanceadvantages of the embodiments.

Fourth Embodiment

FIGS. 6A to 6F are sectional views for explaining steps of amanufacturing method that employs a donor film having theabove-described one configuration example according to a fourthembodiment of the present invention. These sectional views of stepscorrespond to a section of one pixel in the display area. The samecomponents in the fourth embodiment as those in the first embodiment aregiven the same numerals, and a redundant description thereof is omitted.

Referring initially to FIG. 6A, elements such as a thin film transistorTr included in a pixel circuit are formed on a substrate 10, and theseelements are covered by a first insulating film 12. On the firstinsulating film 12, a source electrode interconnect 14 s and a drainelectrode interconnect 14 d that are connected to the thin filmtransistor Tr, and a signal line, power supply line, and so on that areconnected to these interconnects 14 s and 14 d are adequately formed.

A feature of the fourth embodiment is that an auxiliary electrode 50 isformed by using the same layer as the layer of any of theabove-described elements and interconnects. The auxiliary electrode 50may be supplied with a common potential in the display area similarly tothe first embodiment. As shown in the layout diagram of FIG. 3 forexample, the auxiliary electrode 50 is provided on rows and columnsamong lower electrodes 18 to be formed in the next step. Although thedrawing shows a structure in which the auxiliary electrode 50 is formedby using the same layer as the layer of the source electrodeinterconnect 14 s and the drain electrode interconnect 14 d, theauxiliary electrode 50 may be formed by using the same layer as thelayer of another interconnect (not shown).

After the formation of the interconnects including the auxiliaryelectrode 50, a second insulating film 16 is formed on the firstinsulating film 12 in such a manner as to cover these interconnects.This second insulating film 16 may be formed as a planarizationinsulating film like that shown in the drawing, or alternatively may beformed to have a substantially uniform film thickness.

In the second insulating film 16, a connection hole 16 a reaching thedrain electrode interconnect 14 d is formed. At this time, a connectionhole 16 b reaching the auxiliary electrode 50 is simultaneously formed.

Referring next to FIG. 6B, on the second insulating film 16, the lowerelectrode 18 connected to the drain electrode interconnect 14 d isformed in order that the lower electrodes 18 are arranged in a matrix inthe display area. This allows the surface of the lower electrode 18 tobe positioned higher than that of the auxiliary electrode 50. As shownin the layout diagram of FIG. 3, the lower electrodes 18 are disposedamong the auxiliary electrode 50 provided on rows and columns.

After the above-described steps, the steps shown in FIGS. 6C to 6F arecarried out similarly to the first embodiment.

Specifically, referring initially to FIG. 6C, a donor film 1 is disposedon one surface side of the substrate 10 on which the lower electrode 18is formed. Specifically, the organic layer side of the donor film 1 withthe configuration described with FIG. 1 is brought into close contactwith the lower electrode side of the substrate 10. At this time, a gap dis provided between the organic layer 5 and the auxiliary electrode 50exposed at the bottom of the connection hole 16 b. On the other hand,the organic layer 5 is brought into close contact with the lowerelectrode 18 formed on the surface of the second insulating film 16.

In this state, from the donor film side, the part corresponding to thelower electrodes 18 of selected pixels is irradiated with an energy beamsuch as laser light h. Thereby, the organic layer 5 over the donor film1 is selectively transferred onto the lower electrodes 18.

Referring next to FIG. 6D, the donor film 1 is separated from thesubstrate 10.

Thereafter, through repetition of the steps of FIGS. 6C and 6D, theorganic layer 5 for each of the remaining colors is selectively formedon the lower electrodes 18 formed in pixels of a respective one of thecolors.

Subsequently, as shown in FIG. 6E, an upper electrode 30 common to therespective pixels is formed on the whole of the display area over thesubstrate 10. The upper electrode 30 is connected to the auxiliaryelectrode 50.

Thereafter, as shown in FIG. 6F, an insulating or conductive protectivefilm 32 is provided on the upper electrode 30. Furthermore, a countersubstrate 36 is fixed over the protective film 32 with a UV-curableresin 34 according to need, so that a display 52 is completed.

The fourth embodiment can be combined with the first embodiment, and thecombining can enhance advantages of the embodiments.

Fifth Embodiment

FIGS. 7A to 7F are sectional views for explaining steps of amanufacturing method that employs a donor film having theabove-described one configuration example according to a fifthembodiment of the present invention. These sectional views of stepscorrespond to a section of one pixel in the display area. The samecomponents in the fifth embodiment as those in the first embodiment aregiven the same numerals, and a redundant description thereof is omitted.

Referring initially to FIG. 7A, elements such as a thin film transistorTr included in a pixel circuit are formed on a substrate 10, and theseelements are covered by a first insulating film 12. On the firstinsulating film 12, a source electrode interconnect 14 s and a drainelectrode interconnect 14 d that are connected to the thin filmtransistor Tr, and a signal line, power supply line, and so on that areconnected to these interconnects 14 s and 14 d are adequately formed.

Similarly to the fourth embodiment, a feature of the fifth embodiment isalso that an auxiliary electrode 50 is formed by using the same layer asthe layer of any of the above-described elements and interconnects.

After the formation of the interconnects including the auxiliaryelectrode 50, a second insulating film 16 is formed on the firstinsulating film 12 in such a manner as to cover these interconnects.Furthermore, a connection hole 16 a reaching the drain electrodeinterconnect 14 d is formed. This second insulating film 16 may beformed as a planarization insulating film like that shown in thedrawing, or alternatively may be formed to have a substantially uniformfilm thickness.

After the connection hole 16 a reaching the drain electrode interconnect14 d is provided in the second insulating film 16, the lower electrodes18 each connected to the drain electrode interconnect 14 d are so formedon the second insulating film 16 as to be arranged in a matrix in thedisplay area. This allows the surface of the lower electrode 18 to bepositioned higher than that of the auxiliary electrode 50. As shown inthe layout diagram of FIG. 3, the lower electrodes 18 are disposed amongthe auxiliary electrode 50 provided on rows and columns.

Referring next to FIG. 7B, a third insulating film 22 is formed in sucha manner as to cover the lower electrode 18. This third insulating film22 may be formed as a planarization insulating film like that shown inthe drawing, or alternatively may be formed to have a substantiallyuniform film thickness. Through the above-described steps, the lowerelectrode 18 is covered by the third insulating film 22, while theauxiliary electrode 50 is covered by the second insulating film 16 andthe third insulating film 22. Thus, the film thickness of the insulatinglayer on the auxiliary electrode 50 is larger than that on the lowerelectrode 18.

Subsequently, in the third insulating film 22, a opening 22 a thatwidely exposes the center part of the lower electrode 18 with theperipheral edge thereof covered is formed. Furthermore, a connectionhole 22 b′ reaching the auxiliary electrode 50 is formed in the thirdinsulating film 22 and the second insulating film 16. Thus, the depth ofthe connection hole 22 b′ on the auxiliary electrode 50 is larger thanthat of the opening 22 a on the lower electrode 18. In the apertureformation step, it is preferable to carry out etching of which conditionis so set that the taper angle of the sidewall of the opening 22 a willbe set to 30° or smaller.

After the above-described steps, the steps shown in FIGS. 7C to 7F arecarried out similarly to the first embodiment.

Referring initially to FIG. 7C, a donor film 1 is disposed on onesurface side of the substrate 10 on which the lower electrode 18 isformed. The organic layer 5 over the donor film 1 is brought into closecontact with the lower electrode 18 over the substrate 10. At this time,a gap d is provided between the organic layer 5 and the auxiliaryelectrode 50 exposed at the bottom of the connection hole 22 b′, whichis deeper than the opening 22 a. On the other hand, the organic layer 5is brought into close contact with the lower electrode 18 exposed at thebottom of the opening 22 a, which is shallower than the connection hole22 b′.

In this state, an energy beam such as laser light h is emitted from thedonor film side. Thereby, the organic layer 5 over the donor film 1 isselectively transferred onto the lower electrode 18.

Referring next to FIG. 7D, the donor film 1 is separated from thesubstrate 10.

Thereafter, through repetition of the steps of FIGS. 7C and 7D, theorganic layer 5 for each of the remaining colors is selectively formedon the lower electrodes 18 formed in pixels of a respective one of thecolors.

Subsequently, as shown in FIG. 7E, an upper electrode 30 common to therespective pixels is formed on the whole of the display area over thesubstrate 10. The upper electrode 30 is connected to the auxiliaryelectrode 50.

Thereafter, as shown in FIG. 7F, an insulating or conductive protectivefilm 32 is provided on the upper electrode 30. Furthermore, a countersubstrate 36 is fixed over the protective film 32 with a UV-curableresin 34 according to need, so that a display 52 a is completed.

The fifth embodiment can be combined with the first to thirdembodiments, and the combining can enhance advantages of theembodiments.

According to the above-described first to fifth embodiments, in acontact transfer step, irradiation with the laser light h is carried outin the state in which the donor film 1 is brought into close contactwith the lower electrode 18 while a gap d is provided between theauxiliary electrode and the donor film 1. Therefore, even when apositional error of the area irradiated with the laser light h occurs,the organic layer 5 is not transferred onto the auxiliary electrode.

Consequently, enhancements in the luminance and lifetime of the organicelectro-luminescence elements EL can be achieved, and thus thedisplaying performance of the display can be improved.

Modification Example

As one of modification examples of the above-described first to fifthembodiments, a modification example of the fourth embodiment is shown inFIG. 8. As shown in FIG. 8A, a connection hole 16 b in a secondinsulating film 16 that covers an auxiliary electrode 50 may be formedin order that the sidewall of the auxiliary electrode 50 is exposed. Inthis feature, this modification example is different from theabove-described first to fifth embodiments.

After the formation of such a connection hole 16 b, a procedure similarto that of the fourth embodiment is carried out, so that an organicelectro-luminescence element EL is formed as shown in FIG. 8B.Thereafter, as shown in FIG. 8C, a counter substrate 36 is fixed with aprotective film 32 and a UV-curable resin 34, so that a display 52 b iscompleted.

Such a structure can also achieve the same advantages as those of thefourth embodiment.

The concept of this modification example can be applied to the first tothird embodiments and the fifth embodiment as well as to the fourthembodiment. Furthermore, in a configuration in which the opening 22 a isprovided like those shown in the first to third embodiments and thefifth embodiment, the entire face of the lower electrode may be exposedvia the opening 22 a as long as the lower electrode is isolated from theupper electrode by the organic layer formed on the lower electrodethrough transfer.

The above-described respective embodiments (including also themodification example) relate to a procedure of manufacturing of anactive-matrix display. However, embodiments of the present invention canbe applied also to manufacturing of a passive-matrix display in asimilar manner, and can achieve the same advantages.

In a passive-matrix display, as shown in the layout diagram of FIG. 9,lower electrodes 71 are formed to extend in one direction, and anauxiliary electrode 72 is provided among these lower electrodes 71. Thisauxiliary electrode 72 is provided as a common electrode. Furthermore,an upper electrode 73 as a common electrode is provided over the lowerelectrodes 71 and the auxiliary electrode 72. Similarly to anactive-matrix display, organic EL elements are formed by interposing anorganic layer (not shown) between the lower electrodes 71 and the upperelectrode 73 that intersect and overlap with each other. In addition,similarly to an active-matrix display, at the parts where the upperelectrode 73 overlaps over the auxiliary electrode 72, the upperelectrode 73 is connected to the auxiliary electrode 72 via a connectionhole.

In manufacturing of a passive-matrix display having such aconfiguration, by applying any of the above-described embodiments tosteps for forming the lower electrodes 71 and the auxiliary electrode 72and forming the upper electrode 73 to form organic EL elements, the sameadvantages as those of the embodiments can be achieved.

The above-described embodiments are not limited to application to adisplay employing organic EL elements. The embodiments can be widelyapplied to formation of a light-emitting functional layer by a contacttransfer method in manufacturing of a display that includeslight-emitting elements obtained by interposing the light-emittingfunctional layer between an upper electrode and a lower electrode, andhas an auxiliary electrode connected to the upper electrode, and theembodiments can achieve the same advantages.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factor in so far as they arewithin the scope of the appended claims or the equivalents thereof.

1. A display comprising: a plurality of lower electrodes formed over asubstrate; an auxiliary electrode formed between the lower electrodesand having a film thickness which is less than a film thickness of theplurality of lower electrodes; an insulating film formed over thesubstrate and including openings that expose the lower electrodes and aconnection hole that reaches the auxiliary electrode; a light-emittingfunctional layer formed on the lower electrodes exposed via theopenings, the insulating film having a flat surface; and an upperelectrode formed over the lower electrodes and connected to theauxiliary electrode via the connection hole.
 2. The display of claim 1,wherein the relationship t2≧t1+500 nm is satisfied, where t1 is the filmthickness of the plurality of lower electrodes and t2 is the filmthickness of the auxiliary electrode.
 3. A display comprising: aplurality of lower electrodes formed over a substrate; an auxiliaryelectrode formed between the lower electrodes; an insulating film formedover the substrate and including openings that expose the lowerelectrodes and a connection hole that reaches the auxiliary electrode, ataper angle of a sidewall of the connection hole being larger than ataper angle of sidewalls of the openings, and the taper angle of thesidewalls of the openings being equal to or less than 30 degrees; alight-emitting functional layer formed on the lower electrodes exposedvia the openings; and an upper electrode formed over the lowerelectrodes and connected to the auxiliary electrode via the connectionhole.
 4. A display comprising: an auxiliary electrode formed over asubstrate; an insulating film including a connection hole that reachesthe auxiliary electrode and formed over the substrate; a lower electrodeformed on the insulating film; a light-emitting functional layer formedon the lower electrode; and an upper electrode formed over the lowerelectrode and connected to the auxiliary electrode via the connectionhole.